1. Field of the Invention
The present invention relates in general to computers, and more particularly to various embodiments for executing emergency power off/on cycles and resuming normal work in storage systems via a three-stage power up mechanism.
2. Description of the Related Art
In computer storage systems it is common to have multiple storage volumes connected to a single storage volume controller, which is responsible for the reading and writing of data with respect to the storage volumes. All input/output commands for the storage volumes are handled by the volume controller, which also provides a cache memory to speed up portions of the data handling. Power for the overall storage system is provided by a mains electricity supply, with a back-up power supply in the form of a so-called UPS (uninterruptible power supply).
UPS devices effectively function as a battery maintaining a certain amount of charge that will be used when the mains power is cut for any reason. The UPS provides enough power for the storage controller to shut down the system in an orderly manner without any data being lost. The main requirement for the power is the controller's cache, which requires power to maintain the data it stores, and must have its data hardened to some form of permanent storage device, such as the controller's hard disk.